This application addresses broad Challenge Area (05) Comparative Effectiveness Research and specific Topic 05-CA-104* Comparative Effectiveness Research on Cancer Treatment. Effectiveness of prostate cancer treatment has been previously evaluated by Markov models to measure Quality-adjusted Life Expectancy (QALE), but these comparisons did not use prospectively collected HRQOL outcome data to assign transition probabilities for HRQOL health states, and assess effects of such patient baseline function on comparative effectiveness, as we propose herein. Moreover, prior studies have not combined prospective multi-center HRQOL outcomes data with cost analyses to generate estimates of cost-effectiveness comparing the 3 most common contemporary treatments for early stage prostate cancer: prostatectomy, external radiotherapy, and brachytherapy. We propose to address this knowledge gap to facilitate treatment decisions. We hypothesize that baseline health-related quality of life (HRQOL) and clinical characteristics of early stage prostate cancer patients are pivotal determinants of the comparative effectiveness of different treatments. We propose to extend and analyze 2 prospective and one population based cohort including: The PROSTQA cohort, a prospective, multi-center cohort of 1201 early stage prostate cancer patients undergoing primary treatment [Sanda et al in NEJM 2008];the CaPSURE HRQOL cohort, a prospective, multicenter cohort of 2067 early stage prostate cancer patients accrued before being treated at community-based Urology practices nationwide and for whom detailed cost data are available (reported in Wu et al J Urol 2008 and Wilson et al Cancer 2007);and by analysis of costs in 16,757 prostate cancer patients from SEER-Medicare treated by prostatectomy, radiotherapy or brachytherapy from 2003-2005. Three Aims are proposed as follows: Aim 1. To generate and validate models that use pre-treatment HRQOL, clinical status, and treatment details to predict HRQOL changes after each of the three most common primary treatments for early stage prostate cancer: prostatectomy, external radiotherapy, or brachytherapy Aim 2. To construct decision analytic Markov models to predict QALE of primary prostate cancer treatments using prospective cohort data to drive transition probabilities between HRQOL states. Aim 3. To characterize treatment-related costs and combine these with QALE in the Markov model framework to assess overall cost effectiveness as measured by incremental cost-effectiveness ratio (ICER), of prostatectomy, external radiotherapy, or brachytherapy for early stage prostate cancer. The proposed studies will enable combining unique cohorts having extensive HRQOL outcomes data from 3,268 prospectively followed patients with SEER-Medicare data from 16,757 patients to establish a dataset of 20,025 subjects for characterizing how differences in pre-treatment HRQOL and clinical details influence comparative cost effectiveness of different treatments for early stage prostate cancer. This application addresses broad Challenge Area (05) Comparative Effectiveness Research and specific Topic 05-CA-104* Comparative Effectiveness Research on Cancer Treatment: "The results of controlled clinical trials guide recommendations for many initial cancer treatments. But cancer treatments are also prevalent for cancers for which the evidence base in-complete, not applicable to the patient population (e.g. older patients) or non-existent. Prostate cancer is a prime, but not the only example, of this situation. Comparative effectiveness research in this area would use retrospective data and/or prospective interviews with patients, physicians and policy makers to assess the clinical benefits, risks and economic costs of commonly used treatment approaches and assess patient, physician and health system factors that effect dissemination of these treatment approaches." Quality of life is important to prostate cancer patients but efforts to compare different treatments have not previously incorporated differences in patients'quality of life prior to treatment in predicting how patients would do after treatment. We propose to compare effectiveness of different treatments for early prostate cancer (that has not yet spread) while taking into consideration differences in symptoms and quality of life that patients have before treatment.